This invention relates to an automatic winding detection method and apparatus to detect whether a web fed from a feeding means has securely been wound on a reel core.
When automatically winding a web of photographic paper or film which is fed from such feeding means as a roller on a reel core, if the feeding means keeps on supplying the web even though the web has not been securely wound on the reel core, the web might be damaged or wasted as it becomes jammed in the member. It is therefore necessary to detect after a predetermined period of time if the web has really been wound on the reel core and to generate, if necessary, an alarm signal. The feeding means continuously feeds the web until the time it is securely wound on the core but reduces the driving rate thereof or suspends the driving thereafter so as to make the web to be wound on by an intermittent drive. The detection above mentioned is also required for such a switching in driving.
FIGS. 1 and 2 schematically show constructions of prior art devices of checking such winding of the web. In the mechanism shown in FIG. 1, paper 1 fed by a feeding roller 2 is made to abut a winding detection roller 3, is directed to pass between a lower guide 4 and an upper guide 5, and then is wound on a reel core 6 which is revolved by a motor 7. At stationary time, the winding detection roller 3 does not rotate, but as the paper 1 is wound on the reel core 6, the tension caused thereby makes the roller 3 rotate. The rotation thus caused is measured by, for instance, a tachogenerator 8 to sense the rotation moment of the paper 1 on the reel core 6. By judging from the rotational moment caused when the paper is wound on the core 6, the situation of the paper winding can be detected. In the structure shown in FIG. 2, a flexible and curved protrusion 9 is provided on the lower guide 4. The downward tension caused by winding the paper 1 on the core 6 is detected by, for instance, a limit-switch 10 which is so provided as to be engaged with the protrusion 9.
Those conventional web winding detection mechanisms, however, are detrimental in that reel means additionally requires a tachogenerator, a limit-switch or other electric devices, thereby making the structure of the reel part more complicated. The reel part of the device is desirably contained in a magazine structure as a unit so that it may be taken out as soon as the winding ends and new empty reels can be inserted successively. For this purpose, the structure should be simplified sufficiently to allow the detection at the magazine mounting portion and be compact enough to be free of space-consuming electric devices.